• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.713-720
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• 2000

The directional response of strength and deformation on the rocks acting by external loads is called by strength and deformability anisotropy, respectively. Peak strength and its failure criteria of anisotro rocks have been studied and reported. Many authors have investigated in detail the behavior of triaxial peak strength of anisotropic rocks(Jaeger 1960, McLamore & Gray 1967, Hoek & Brown 1980, Ramamurthy & Rao 1985). They concluded that the triaxial strength of anisotropic rocks varies according to the inclination of discontinuity in specimens. And, the minimun triaxial strength occurs in the specmen with 60° of inclination angle ; and specimens with 0° or 90° inclination have maximum triaxial strength. Based on the experimental result, the behavior triaxial strength is investigated. The triaxial compression tests due to the angle bedding plane have been conducted and the material constants, 'm' and 's', cohesion and angle of friction and nonlinear strength parameters to fit for the failure criterion were derived from the regression analysis. And, the experimental date are employed to examine three existing failure criteria for peak strength, provided by Jaeger, McLamore and Hoek & Brown and Ramamurthy & Rao. For a shale, the suitability of the failure criteiria of triaxial peak strength for anisotropic rocks is discussed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.569-576
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• 2000

This study performs a series of Triaxial Compression Test for clay-sand composite specimens changing area replacement ratio. Purpose of the test is to conform the propriety of weighted average method in estimating shear strength of the composite ground. The test results show that measured values of shear strength of composite specimens are larger by 20∼30% than those from estimation using the current weighted average method. It is thought that the differences are from pseudo-overconsolidation behavior of composite specimens.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.189-196
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• 2002

According to the Korean Design Code for port and harbor facilaties, bearing capacity of rubble mound under eccentric and inclined load is calculated by the simplified Bishop method, and strength parameters are recommended to be c=0.2kg/$\textrm{cm}^2$ and ø=35$^{\circ}$for standard rubble if the compressive strength of parent rock is greater than 300kg/$\textrm{cm}^2$, quoting from research results by Jun-ichi Mizukami(1991), But this facts have never been certified in Korea because there was not large-scale triaxial test apparatus until 2000 in Korea. Firstly in Korea, the large-scale triaxial test (sample diameter, 30cm and height, 60cm) on the rubble originated from porous basalt rock in North-Cheju was accomplished. Then strength parameters for basalt rubble produced in North-Cheju are recommended to be c=0.3kg/$\textrm{cm}^2$ and ø=36$^{\circ}$if the compressive strength of parent rock is greater than 400kg/$\textrm{cm}^2$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.71-78
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• 2000

SHANSEP method involves the consolidation to stresses in excess of the preconsolidation pressure in order to overcome sample disturbance effect. The concept of SHANSEP is based on an approach to laboratory test which attempts to reproduce the in-situ conditions more closely than is possible in routine tests and evaluates normalized strength parameters for the soil as a function of OCR. But SHANSEP method can be applied only to fairly uniform clay deposits, and is unsuitable for a random deposit. In this study, CK/sub o/U triaxial compression test and incremental loading consolidation test were performed for the application of SHANSEP method on Yangsan clay. During the K/sub o/-consolidation, triaxial specimens were consolidated to stress equal to two times the in-situ vertical effective stress. And for overconsolidated condition, the specimens were swelled to a known vertical effective stress in order to have the desired OCR. With the results of CK/sub o/U triaxial compression test using the block samples, the relationship between c/sub u//σ/sub vc/' and OCR on Yangsan clay was established. For evaluating the undrained shear strength of Yangsan clay with depth, CK/sub o/U triaxial compression test was performed using the piston samples taken from Yangsan site. And also undrained shear strength was analyzed from the in-situ test such as Cone Penetration Test(CPT), Dilatometer Test(DMT), and Field Vane Test(FVT) and was compared with that of CK/sub o/U triaxial compression test.

• 한국철도학회논문집
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• 제13권1호
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• pp.84-91
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• 2010

본 연구에서는 철도, 도로 등 대형 성토지반구조물의 주요 지반재료인 입경이 큰 조립재료에 대해 전단강도, 변형계수, 응력-변형 거동과 같은 지반공학적 설계정수를 평가 산정할 수 있는 대형삼축압축시험장비를 구축하고, 이를 활용한 도상자갈재료에 대한 정적삼축압축시험 결과를 통해 그 의미와 적용 가능성을 제시하였다. 도상자갈과 같이 지표면에 설치되어 포화 가능성이 낮고, 구속압이 작은 경우에는 진공압(vacuum)으로 구속압을 제어하는 방식이 효과적임을 확인할 수 있었다. 도상자갈 재료의 삼축압축시험 결과로부터 구속압별 전단강도, 변형계수, 입자파쇄 영향 등의 합리적인 결과와 경향을 확인하였으며, 모암의 입자강도, 구속압 등의 영향을 고려하여 전단강도 포락선을 예측할 수 있는 비선형식에 적합한 재료 상수를 산정, 적용하여 실험 결과를 근접하게 재현해낼 수 있었다.

• 한국농공학회논문집
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• 제52권3호
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• pp.73-79
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• 2010

In the present study, the loading frequency dependencies of cyclic shear strength and elastic shear modulus of reconstituted clay were examined by performing undrained cyclic triaxial tests and undrained cyclic triaxial tests to determine deformation properties. The result of undrained cyclic triaxial test of reconstituted and saturated clay shows that a faster frequency leads to higher stress amplitude ratio, but when the frequency becomes fast up to a certain point, the stress amplitude ratio will reach its maximum limit and the frequency dependence becomes insignificant. And also, the result of undrained cyclic triaxial deformation test shows a fact that a faster loading frequency leads to higher equivalent shear modules and smaller hysteresis damping ratio, and confirms the frequency dependence of cohesive soil. Meanwhile, the result of the creep test shows that continuing creep is created in the undrained cyclic triaxial test with slow loading frequency rate, and since loading rate becomes slower at the vicinity of the maximum and the minimum deviator stress due to sine wave loading, the vicinity of the maximum and the minimum deviator stress shall be more influenced by creep.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.402-413
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• 2006

Strength evaluation of soft soils is a formidable task because of difficulties in sampling, specimen preparation and setting in triaxial cells. In undrained triaxial testing, sampling disturbance, verticality of specimen and bedding effect give a great influence on shear strength measurements. In the other hand, shear wave measurements of specimens are less influenced by these factors. In this research, the bender elements were attached top cap and base pedestal of triaxial cell and shear wave velocities were measured. To initiate a methodology to evaluate shear strength indirectly by measuring shear wave velocity, a relationship between shear strength and shear wave velocity was developed with kaolinite specimens consolidated in the laboratory. Undrained shear strength turns out to increase linearly with shear wave velocity. Stress-strain curves can also be predicted with a hyperbolic model and shear wave measurements.

• Geomechanics and Engineering
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• 제4권4호
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• pp.251-262
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• 2012

Triaxial tests are essential to estimate the shear strength properties of the soil or rock. Normally triaxial tests are carried out on samples of 38 mm diameter and 76 mm height. Granular materials, predominantly used in base/sub-base construction of pavements or in railways have size range of 60-75 mm. Determination of shear strength parameters of those materials can be made possible only through triaxial tests on large diameter samples. This paper describes a large diameter cyclic triaxial testing facility set up in the Geotechnical Engineering lab of Indian Institute of Science. This setup consists of 100 kN capacity dynamic loading frame, which facilitates testing of samples of up to 300 mm diameter and 600 mm height. The loading ram can be actuated up to a maximum frequency of 10 Hz, with maximum amplitude of 100 mm. The setup is capable of carrying out static as well as dynamic triaxial tests under isotropic, anisotropic conditions with a maximum confining pressure of 1 MPa. Working with this setup is a difficult task because of the size of the sample. In this paper, a detailed discussion on the various problems encountered during the initial testing using the equipment, the ideas and solutions adopted to solve them are presented. Pilot experiments on granular sub-base material of 53 mm down size are also presented.

• Geomechanics and Engineering
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• 제21권4호
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• pp.327-336
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• 2020

Conventional researches on the behavior of fiber-reinforced and unreinforced soils often investigated the failure point. In this study, a concept is proposed in the comparison of the fiber-reinforced with unreinforced sand, by estimating the strength and strength ratio at different levels of strain. A comprehensive program of laboratory drained triaxial compression test was performed on compacted sand specimens, with and without date palm fiber. The fiber inclusion used in triaxial test specimens was form 0.25%-1.0% of the sand dry weight. The effect of the fiber inclusion and confining pressure at 0.5%, 1.0%, 1.5%, 3.0%, 6.0%, 9.0%, 12%, and 15% of the imposed strain levels on the specimen were considered and described. The results showed that, the trend and magnitude of the strength ratio is different for various strain levels. It also implies that, using failure strength from peak point or the strength corresponding to the axial strain of approximately 15% for evaluating the enhancement of strength or strength ratio, due to the reinforcement, may cause hazard and uncertainty in practical design. Therefore, it is necessary to consider the strength of fiber-reinforced specimen at the imposed strain level, compared to the unreinforced specimen.

• 대한토목학회논문집
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• 제34권3호
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• pp.947-954
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• 2014

일반적으로 Mohr-Coulomb 파괴 이론을 바탕으로 한 재료 파괴는 최대수직응력이나 최대전단응력 상태에서 파괴가 일어나는 것이 아니라 수직응력과 전단응력의 임계결합상태에서 파괴된다. 이에 본 연구에서는 배수성 아스팔트 혼합물 2종과 SMA 10mm혼합물 및 일반 밀입도 아스팔트 19mm를 이용한 $45^{\circ}C$와 $60^{\circ}C$에서 삼축압축시험을 실시하였다. Mohr-Coulomb의 파괴 이론을 바탕으로 삼축압축시험 결과를 정리한 결과 내부마찰각은 $38.9^{\circ}{\sim}46.9^{\circ}$로 다소 불규칙하게 측정되었으나 점착력의 경우 온도와 시편의 수침여부에 따라 다르게 나타났다. 또한, 아스팔트 혼합물의 간접인장강도시험과 삼축압축시험 상관관계를 알아보기 위해 삼축압축시험 결과로 평가된 점착력과 내부마찰각을 이용하여 계산된 이론적인 간접인장강도와 시험을 통해 직접 측정된 간접인장강도를 분석하였다. 두 간접인장강도 값은 비례하는 경향을 보였다.